Projectile



July 7, 1942. w. BORN 2,288,604

PRoJEoTILE y Filed March 21, 1939 2 Sheets-Sheet l By I dm@- July 7, 1942. w. BORN 2,288,604

PROJEOTILE Filed March 2l, 1939 2 Sheets-Sheet 2 Allo/'nay Patented July 1.1942

parte star S PAT PE FFESE Application March 21, 1939, Serial No. 263,256 In Germany September 28, 1935 3 Claims.

This invention relates to a fire arm and has particular reference to a projectile for a bullet and barrel system in which the bullet or pro-l jectile is deformed during its passage through the barrel froma larger initial calibre or maximum diameter down to a smaller muzzle calibre, in order to increase the propelling force imparted to the bullet.

It is an object of the present invention to provide a. projectile for a bullet and barrel combination in which the bullet irrespective of the large deforming forces acting upon it is only deformed in a predetermined ballistically favourable manner, 'without assuming any undesirable shape or destruction.

Another object of the invention is to provide a deformable projectile which prevents the production of excessive gas pressures in the barrel and ensures an emcient guiding and centering action of the barrel on the cylindrical part of the buiiet and high firing precision.

Still another object of the invention is to construct the deformable projectile in such a manner that the energy required for its deformation is kept within moderate limits.

Still another object ci the invention is to prevent inflation, swelling or jamming of the bullet and e pecially of its-core due to the upsetting crescere exerted upon it by the powder gases.

with these and other objects in View, as may become apparent from the within disclosures, the invention consists not only in the structures herein pointed out and illustrated by the drawings, out includes further structures coming within the scope of what hereinafter may be ciainied.

The character oi the invention, however, may

he cest understood by reference to certain of its4 cross-sectional View of the same reifen et line lei-E, 2. showing she-ws e modifie-:l bullet having s. eiosed i shows e 'collet inclu i Sii;

stesi jacket additional jacket having hollow innathe same projectile after its tie- Fig. 5 shows a bullet in which the outer' jacket is drawn directly over the steel core.

Fig'.` 6 shows a bullet in which a layer of a plastic material is interposed between the outer jacket and the steel core.

Fig. 7 shows Ia bullet in which the outer cover is provided with one bulbed portion only for obtaining a stream line final shape of the bullet Figs. 8 to 12 are exaggerated fragmentary axial sections of embodiments of a barrel and bullet system employing the projectile of my invention.

Fig. 8 shows a barrel in which the tapered portions of the lands extend into the conica part of the barrel.

Fig. 9 shows a barrel in which the lands extend further into the conical part of the barrel.

Fig. l0 shows e. barrel in which the conical portion has two different tapers, the maximum taperibeing immediately in front of the cartridge magazine or breech chamber.

Fig. l1 shows a barrel in which the taper follows a curve, having its maximum taper near the breech chamber. y

Fig. l2 shows a barrel similar to Fig. 11, but with the maximum taper at the end of the conical part.

Referring now to the drawings in greater detail, and first to Figs. i to 3, it will be seen that a core l of lead or the like is surrounded by a normal cover or jacket 2 in known manner. In addition. an outer jacket 3 is drawn overt-he jacket 2 from the top end and surrounds the cylindrical part of the same in the form 'of two annular bulged or bulbed portions l.' in the bulbed state of the outer cover there is an axiai spacing left between the rear edge oi the same and the end edge oi the bullet while in a radial direction the end edge of the outer cover engages tightly the body oi the bullet. During the .pe-ssage of mynovel builet through the conical portion of a barrel of the type shown in Figs. 8 to l2, the bulbed portions of the outer `iaclret are compressed or depressed tothe cyiindrlcal form shown in Fig. 2 and due to the drawing and stretching action involved therein the jacket 3 becomes longer. preferably so chosen that the end edges oi the cuter aciret and of the core oi the toilet coincide with each other in the final oylindricai or smooth state ci the jacket as shown Fig. 2. The hollou7 spaces between the portions and the inner jacket have new disappeared, the outer jacket surrounds the inner jacket smoothiy andthe shape of the projectile is new exactly siraiiar to that oi en ordinary jacket huilet,

The dimensions are .f

- bullet as in the above describedtypes.

passage through the barrel the bulbed portion is.

The 'p'ovision of the buibed portions in an outer -jacket ofA the 4bullet and the additional provision of a normal, vrtightly fitting inner jacket 2 are important features of my invention.

By way of alternative, the normal jacket 2 of the bullet may be closed at the rearl end of the same, so as to protect the softer core of the bullet against the direct action of the powder gas, as shown in Fig. 3. l

In the preferred form of my novel bullet only the outer jacket 3 and its bulbed portions are subjected to the deformation required to eiect the requisite guiding of the bullet in the lands and grooves of the rifled portion of the barrel. To this end, the maximum cross section or calibre of the portion of the bullet inside the outer jacket is made smaller than the smallest calibre or cross section within the lands in the cylindrical portion of the barrel. This offers the advantage that the outer jacket if desired may be applied directly on the steel or like core of ordnance projectiles or the like, in the manner shown in Fig. 5. l

On the other hand, it is also possible in bullets having a steel core and an outer jacket 3, to provide a thin layer of easily deformable or plastic material, 8, Fig. 6, such as soft lead or hard lead and the like between the outer jacket Sand' the core 6, or even to completely fill up the hollow spaces within the bulbed portions by such a material. The intermediate layer 8 is then drawn out in the passage of the bullet through the barrel and assumes the` full length ofthe bullet, thus acting as a lubricant or antifriction means for they bullet.l A further advantage" is attained by the easily deformable intermediate layer in that in case of vlarge tolerances of thebullet .diameter and an excessive diameter of some bul-l lets, the steel core is not jammed in the barrel but the dllerence is compensated by deformation or displacement of the soft intermediate layer 8.

A bullet of a ballistically favourable tear or torpedo shapemay be obtained by a construction as shown in Fig. 7. lIn this case, the bullet I with its jacket 9 which may be slightly torpedoory tear-shaped, is provided with an outer cover II that is drawn over the jacket 9 from the-top end thereof and bulged or arched from the point I2 where the forwardly tapered front end of the projectile passes over into the middle and rear part thereof, towards the end of the projectile, in the form of a single bulb I3 the barrel.

followed by a cylindrical guidance for vthe bullet. Instead of making the normal tapered part of the barrel longer it is also possible to provide a separateconical portion between the normal tapered portion and the cylindrical portion ofthe I prefer to make said conical part with a smooth unried bore in order to avoid any undue resistance oiered against acceleration of the projectile in addition to the resistance due to the deformation work.

A barrel of this kind is shown in Fig. 8. The conical part Il in this case begins right in front of the breech chamber I5 and bullet space I9 and has a maximum calibre corresponding to the,

portion I6 is rilied at I7 and thelands taper oii in the conical part I4, over adistance I8, in a similar'manner as with the conventional barrels.

Where the manufacturing tolerances to be ad- Y mitted for the barrel and bullet c'alibre are large,

it may be required that the riiiing extends further into the conical part I4 by a distance I8', Fig. 9, and in some instances to a point near the cartridge magazine l5, in order to ensure the required degree of firing precision. In this case,y

the lands are so formed, if possible, thatthe grooving or channelling work exerted with respect to the outer jacket is `kept at a low rate. -To

' this end, the lands maybe formed toV rise quite gradually from the inner walls'of the barrel, as

. to their height and width, witha very small n,height and their nal twist.

In order to ensure high resulting precisionit is required thatthe front bulb of the outer jacket rear end of which tightly engages the body of the In its compressed only to such an extent that the end edge of the outer jacket II coincides with the end edge of the normal jacket 9, while a certain clearance is left at the bulbed portion so that the bullet leaves the barrel in a tear-shaped form underlying favourable aerodynamic conditions.

In order to obtain the required increase of the ballistic effect with projectiles such as described the barrels from which the projectiles are fired one depth of the rifling or grooves at 3 to 5 calibre lengths or 1:80 to 1:100. The tapered part is u Accordingly, the real bullet bodies or any porin the breech chamber.

is guided and centered in the conical partl of the barrel already after a very short travelling dis- A tance and while the rear bulb is still being guided In order to producesuch early guiding action with larger working tolerances I may provide the conical portion of the bore inthe barrel with a high initial taper in front of the breech chamber I5, for example, in the manner shown in Fig. 10 in which a. short conical connecting portion 20 of an increased taper or pitch is provided between the long conicalportion of the barrel. bore may have a taper followingv a non-linear, curved characteristic having its maximum taper or pitch near the breech chamber or near the muzzle end, as shown by way of example at 2l in Figs. l1 and l2, respectively, whereby the special features, more particularly the explosion speed, of the respective gun-powder may be met or a rapid initial acceleration of the bullet may be effected.

, It Will thus be understood from the foregoing that in such a barrel and bullet system the deformation of the projectile is eifected by drawing out and depressing an additional outer jacket on the projectile body and the lands are so shaped and-dimensioned withv respect'to the wall thickness of the outer jacket as to form grooves in said outer jacket only, without entering too deeply into the same or even cutting through the same.

tions or projections or rings of the same are not subjectedto deformation in 'the barreland bullet system embodying my invention, as distinct from known systems of this kind.

This will be seen best from Fig. 2a, showing a cross sectional view through my novel projectile on the line A-B in Fig. 2, as it leaves the barrel which is shown in an end view. As shown in this figure, the core i and the inner or normal.

jacket 2 are not deformed at all, while the outer jacket 3 has been deformed and depressed into tight engagement with the inner jacket. Also, the lands IB between the grooves Il of the rifling have formed corresponding channels or grooves in the outer jacket while intermediate the lands the engagement between the jackets 2 and 3 is less tight. The portion of the barrel in which the rst acceleration and deformation is imparted to the projectile is made without any twist of the riiling, if any, in order to ensure that the outer jacket will be drawn out smoothly and exactly in the direction of the axis of the projectile, whereby the resulting precision is enhanced.

The smooth shape of the bullet core prevents the outer jacket from getting stuck at any intermediate point of the core and ensures a smooth sliding of the outer jacket along the core. Moreover, due to the provision of a separate normal.

core of a material liable to be deformed under the explosive action of the associated charge, an inner jacket surrounding said core for preventing deformation of the same and an outer jacket which tightly engages said inner jacket at its front end and slidably at its rear end and is bulged out intermediate said ends in the form of at least one annular bulb, said bulbed portion being adapted to be depressed into intimate engagement with said nnerfjacket, with sliding movement of the rear end of said outer jacket on said inner jacket, by passage through said barrel.

2. For cooperation with a barrel having a tapered bore portion, a projectile comprising a core of a material liable to be deformed under the' explosive action of the associated charge, an inner jacket surrounding said core on all sides for preventing deformation of the same and an outer jacket which tightly engages said inner jacket at its front and rear ends and is bulged out in the vform of at least one annular bulb, said bulbed i respect to said core adjacent the rear end there- WALDEMAR BORN. 

